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Industrial Chemical Found in Many Waters and Lands

December 9, 2009

Thousands of chemicals can contaminate drinking water and ground water, but less than 100 are regularly tracked in drinking water, and only a few hundred are sporadically checked in ground or surface water. Some of the thousands of potential contaminants are poorly tracked even though they are known to be significantly toxic and sometimes occur at very high concentrations in waters of concern.

One of these is dinitrotoluene (DNT), a synthetic compound that is used primarily to make polyurethane products found in goods such as bedding and furniture, as well as in explosives, ammunition, dyes, and air bags.

Toxicity studies in people and animals have found that DNT is a known animal carcinogen, and can damage the kidneys and the cardiovascular, neurological, gastrointestinal, and reproductive systems.

There are six known forms, or isomers, of DNT: 2,4-DNT and 2,6-DNT, which make up more than 90% of the DNT used, and 2,3-DNT, 2,5-DNT, 3,4-DNT, and 3,5-DNT. The best available health and tracking data are for 2,4-DNT and 2,6-DNT, but limited data suggests to many public health officials that the other four isomers pose a similar toxicological threat. In the rankings of toxicity developed for the Superfund program, 2,4-DNT is ranked 94th out of 275 substances listed, and 2,6-DNT is ranked 261st.

Addendum to toxicological information, published October 2009 by the CDC's Agency for Toxic Substances and Disease Registry (includes numerous pieces of new and updated information related to issues such as toxicity, genetic variations in vulnerability, and environmental fate. Source: Dr. Obaid Faroon, ATSDR Division of Toxicology and Environmental Medicine).

For a number of years, EPA considered setting a standard for DNT, and requiring that it be monitored in drinking water. However, in July 2008 the Bush administration decided that such steps weren't warranted, after concluding that the chemical didn't pose a significant, widespread threat.

Residents around the Badger Army Ammunition Plant in Baraboo, WI, have been pushing for several years to have the state of Wisconsin develop a standard, after DNT was found in high concentrations in many drinking water and monitoring wells in and around the facility. The Wisconsin Department of Natural Resources is recommending a standard for all isomers combined of 0.05 ppb. This is far lower than the concentrations that have been found in the wells, where peak concentrations of just one of the isomers or another have been several or many orders of magnitude higher than the proposed combined standard, ranging from 1.5 to 2,200 ppb.

The US Army told the state in 2007 that setting a standard that combined all isomers was inappropriate, given the evidence available at the time. The Army's stance was based on DNT's carcinogenic potential, and didn't address other health concerns. The Army continues to monitor the Wisconsin process.

Public hearings will be held in Madison (Dec. 11, 2009), Baraboo (Dec. 14), Eau Claire (Dec. 15), Stevens Point (Dec. 15), and Oshkosh (Dec. 16), and the public comment period will close Dec. 30, 2009. After that, the state will consider comments received and could create a proposed rule, after which the legislature might approve a standard some time in 2010 or 2011.

No other states have formally contacted the Wisconsin Department of Natural Resources, says spokesman Mike Lemcke, 608-266-2104, but some observers speculate that a number of states will be watching what happens in Wisconsin as they consider setting their own standard.

Nationwide monitoring for DNT is limited, but there are many known occurrences in and around military sites, industrial settings, and other areas.

EPA has identified at least 76 contaminated sites in 26 states. In the accompanying spreadsheet provided by the agency, sites highlighted in yellow have surface water or ground water contamination. The others have contamination in soils or other media.

2,4-DNT is a high production volume (HPV) chemical, meaning that it is annually made or imported into the US in quantities exceeding 1 million pounds. However, EPA has not included it in its HPV Challenge Program, which is an effort to have industry voluntarily provide toxicity data, because it has been included in the Screening Information Data Set program operated under the auspices of the Organization for Economic Cooperation and Development (OECD).

CDC's Agency for Toxic Substances and Disease Registry (ATSDR) says that, to the best of its knowledge, it's appropriate to assume there are at least 122 Superfund sites contaminated to some extent with DNT. However, note on the spreadsheet provided by ATSDR that is linked to below that some of these sites are at the same facility, but are separated by the DNT isomer identified, possibly reducing the total number of DNT-contaminated Superfund facilities. On the other hand, there could easily be more, since not all Superfund sites have been tested for DNT (nor have many other known hazardous sites). Adding to this difficulty, several components of ATSDR's site mapping and data systems are broken at the moment, so it can't currently identify all of the Superfund sites. The ones it can identify tend to be very similar to those identified by EPA, but note that the Badger site in WI is on the ATSDR list, but not the EPA list, confirming discrepancies in available information.

Along with these sites, CSWAB has reviewed various data bases and says DNT contamination also occurs in the following sites (listed by EPA Region), some of which are different from those identified in the EPA and ATSDR spreadsheets:

The US Geological Survey has conducted some testing for DNT, and found 2,4-DNT in 1.2% of about 2,000 samples, and 2,6-DNT in 2.5% of the samples. In streambed sediments, 2,4-DNT was in 0.3% of 900 samples, and 2,6-DNT was in 1.2% of 500 samples. To find out more about the findings, and sample locations, contact Donna Myers, 571-643-3030. USGS did not include DNT in its recently-completed nationwide testing of 219 contaminants in drinking water wells.

Additional environmental sources are the known manufacturing sites in eight states (AR, IA, IN, KY, LA, NY, OH, VA), which together acknowledged 14,937 pounds of releases and 595,531 pounds of waste in 2007.

Pulling together all these sources of information, and tracking down other sources such as state-generated data, may provide a more complete picture of the DNT threat to health and the environment than is currently known to federal, state, and local officials.